Angel food cake, or angel cake, is a type of sponge cake made withegg whites, flour, and sugar. A whipping agent, such as cream oftartar is commonly added. It differs from other cakes because ituses no butter. Its structure comes from whipped egg whites knownas a protein foam. Angel food cake originated in the United Statesand first became popular in the late 19th century.[2] It gained itsunique reputation along with its name due to its light and fluffytexture, said to resemble the "food of the angels".